1. Field of the Invention
The present invention relates to an actinic ray-sensitive or radiation-sensitive resin composition that undergoes a reaction when exposed to actinic rays or radiation thereby changing its properties, and also relates to a method of forming a pattern therewith. More particularly, the present invention relates to an actinic ray-sensitive or radiation-sensitive resin composition for use in a production of a semiconductor such as an IC and a production of a circuit board for a thermal head, a liquid crystal and the like; for use in other photofabrication processes; for use in a production of a lithographic printing plate; and for use as an acid-setting composition; and also relates to a method of forming a pattern therewith.
In the present invention, the terms “actinic rays” and “radiation” mean, for example, a mercury lamp bright line spectrum, far ultraviolet rays represented by an excimer laser, extreme ultraviolet rays, X-rays, electron beams and the like. In the present invention, the term “light” means actinic rays or radiation.
2. Description of the Related Art
A chemical amplification resist is capable of, upon exposure to far ultraviolet rays or other radiation, generating an acid at the exposed area. A reaction catalyzed by the generated acid allow the solubility of the exposed area in a developer to be different from that of the non-exposed area. The difference in the solubility between those areas makes it possible to attain pattern formation on a substrate.
In using a KrF excimer laser as an exposure light source, a resin whose fundamental skeleton consists of a poly(hydroxystyrene) exhibiting a low absorption mainly in the region of 248 nm is employed as a major component. Accordingly, favorable pattern with high sensitivity and high resolving power can be formed. Thus, a system superior to the conventional naphthoquinone diazide/novolak resin system has been realized.
On the other hand, in using a light source of a further shorter wavelength, for example, an ArF excimer laser (193 nm) as an exposure light source, the above-mentioned chemical amplification system has not been satisfactory because the compounds having an aromatic group inherently exhibit a sharp absorption in the region around 193 nm.
Therefore, various resists for an ArF excimer laser containing an alicyclic hydrocarbon structure have been developed. However, the current situation is that it is extremely difficult to discover an appropriate combination among an employed resin, a photoacid generator, an additive and a solvent, etc., from the viewpoint of the comprehensive performance of a resist. Further, in the formation of a fine pattern whose line width is, for example, 65 nm or less, it has been demanded to improve line edge roughness performance of line-pattern and resolving power.
It has been found that the resolving power and line edge roughness performance can be improved by incorporation of a repeating unit having a specific lactone structure in a resin with the above alicyclic hydrocarbon structure. For example, Jpn. Pat. Appln. KOKAI Publication No. (hereinafter referred to as JP-A-) 2005-352466 and JP-A-2004-210917 describe resist compositions containing resins having specific lactone repeating units in which a spacer is introduced between the polymer principal chain and the lactone skeleton. Further, JP-A-2008-31298 describes that not only the resolving power and line edge roughness but also the dependency on density distribution and exposure margin can be improved by use of a resist composition containing a resin having a specific lactone repeating unit in which a similar spacer is incorporated.
Still further, JP-A-2003-5375, JP-A-2003-255537 and JP-A-2003-252933 disclose compositions characterized by containing resins obtained by copolymerization of two or more types of lactone monomers.
However, in view of the most recent developments in which use is made of a line width of 45 nm or less and to which a liquid immersion process is applied, it is demanded to raise the level of relevant technology. Accordingly, the above-mentioned prior art is not always satisfactory and the current situation is that deficiency is encountered not only in the Line Width Roughness (LWR) but also in the exposure latitude and Mask Enhancement Error Factor (MEEF).